<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.bootcss.com/jquery/3.4.1/jquery.js"></script>
    <script type="text/javascript" src="http://localhost/Service.ashx?callback=jsonpCallback"></script>
</head>
<body>
   <div class="head">
       <a href="html/html.html">html</a>
       <a href="html/css.html">css</a>
   </div>
   <div id="app">

   </div>
   <div class="footer">
      footer
   </div>
   <script>
       /* 
       return false  阻止a标签的跳转
        */
        /* 
        load()加载服务器上的数据
         */
       var htmls = ["html/html.html","html/css.html"];
       $("#app").load(htmls[0])
       $(".head a").click(function(){
           $("#app").load(htmls[$(this).index()])
           return false;
       })
   </script>
</body>
</html>